Tracing Embedded Stellar Populations in Clusters and Galaxies Using Molecular Emission: Methanol as a Signature of the Low-Mass End of the Imf

Kristensen, L. E.; Bergin, Edwin A.

doi:10.1088/2041-8205/807/2/l25

Cited by 4 publications

(4 citation statements)

References 27 publications

(36 reference statements)

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“…The detection of widespread high-J CHO H 3 emission around the highest-mass protostars suggests that the use of CHO H 3 as a bulk outflow tracer as suggested by Kristensen & Bergin (2015) is not viable in regions with forming high-mass stars. While mid-J CHO H 3 emission associated with the outflow (e.g., the J=10-9 transition) is detected, it is completely dominated by the general "extended hot core" emission described in Section 3.3.…”

Section: Outflowsmentioning

confidence: 99%

Thermal Feedback in the High-mass Star- and Cluster-forming Region W51

Ginsburg

Goddi

Kruijssen

et al. 2017

ApJ

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Thermal Feedback in the High-mass Star-and Cluster-forming Region W51http://researchonline.ljmu.ac.uk/7346/ Article LJMU has developed LJMU Research Online for users to access the research output of the University more effectively. Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Users may download and/or print one copy of any article(s) in LJMU Research Online to facilitate their private study or for non-commercial research. You may not engage in further distribution of the material or use it for any profit-making activities or any commercial gain.The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription. LJMU Research OnlineThermal Feedback in the High-mass Star-and Cluster-forming Region W51 Abstract High-mass stars have generally been assumed to accrete most of their mass while already contracted onto the main sequence, but this hypothesis has not been observationally tested. We present ALMA observations of a3 1.5 pc area in the W51 high-mass star-forming complex. We identify dust continuum sources and measure the gas and dust temperature through both rotational diagram modeling of CHO H 3 and brightness-temperature-based limits. The observed region contains three high-mass YSOs that appear to be at the earliest stages of their formation, with no signs of ionizing radiation from their central sources. The data reveal high gas and dust temperatures ( > T 100 K) extending out to about 5000 au from each of these sources. There are no clear signs of disks or rotating structures down to our 1000 au resolution. The extended warm gas provides evidence that, during the process of forming, these high-mass stars heat a large volume and correspondingly large mass of gas in their surroundings, inhibiting fragmentation and therefore keeping a large reservoir available to feed from. By contrast, the more mature massive stars that illuminate compact H II regions have little effect on their surrounding dense gas, suggesting that these main-sequence stars have completed most or all of their accretion. The high luminosity of the massive protostars ( > L 10 4  L ), combined with a lack of centimeter continuum emission from these sources, implies that they are not on the main sequence while they accrete the majority of their mass; instead, they may be bloated and cool.

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Section: Outflowsmentioning

confidence: 99%

Thermal Feedback in the High-mass Star- and Cluster-forming Region W51

Ginsburg

Goddi

Kruijssen

et al. 2017

ApJ

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“…The GMCs to be passed to the next steps of the simulation are chosen randomly from the mass distribution, and each GMC mass acts as an initial cluster mass, i.e., one GMC will form one cluster in the model. Before the GMC mass is passed to the cluster module (based on the cluster-in-a-box model by Kristensen & Bergin 2015), each cloud is assigned an age based on its free-fall time, which is then randomly scaled between being newly formed and completely collapsed. This affects the number of deeply embedded protostars (Class 0 and I protostars) driving outflows in a given cloud.…”

Section: Appendix A: Overview Of the Galaxy-in-a-box Modelmentioning

confidence: 99%

Star-formation-rate estimates from water emission

Dutkowska¹,

Kristensen²

2023

A&A

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Context. The star-formation rate (SFR) quantitatively describes the star-formation process in galaxies throughout cosmic history. Current ways to calibrate this rate do not usually employ observational methods accounting for the low-mass end of stellar populations as their signatures are too weak. Aims. Accessing the bulk of protostellar activity within galactic star-forming regions can be achieved by tracing signposts of ongoing star formation. One such signpost is molecular outflows, which are particularly strong at the earliest stages of star formation. These outflows are bright in molecular emission, which is readily observable. We propose to utilize the protostellar outflow emission as a tracer of the SFR. Methods. In this work, we introduce a novel version of the galaxy-in-a-box model, which can be used to relate molecular emission from star formation in galaxies with the SFR. We measured the predicted para-water emission at 988 GHz (which is particularly bright in outflows) and corresponding SFRs for galaxies with LFIR = 108 − 1011 L⊙ in a distance-independent manner, and compared them with expectations from observations. Results. We evaluated the derived results by varying star-forming parameters, namely the star formation efficiency, the free-fall time scaling factor, and the initial mass function. We observe that for the chosen water transition, relying on the current Galactic observations and star formation properties, we are underestimating the total galactic emission, while overestimating the SFRs, particularly for more starburst-like configurations. Conclusions. The current version of the galaxy-in-a-box model only accounts for a limited number of processes and configurations, that is, it focuses on ongoing star formation in massive young clusters in a spiral galaxy. Therefore, the inferred results, which underestimate the emission and overestimate the SFR, are not surprising: known sources of emission are not included in the model. To improve the results, the next version of the model needs to include a more detailed treatment of the entire galactic ecosystem and other processes that would contribute to the emission. Thus, the galaxy-in-a-box model is a promising step toward unveiling the star-forming properties of galaxies across cosmic time.

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“…Studies show that there is a proportionality between this emission and protostellar envelope mass (e.g., Bontemps et al 1996;Skretas & Kristensen 2022). Kristensen & Bergin (2015) utilized this link to construct the cluster-in-a-box model 1 , simulating methanol emission from low-mass outflows in embedded star-forming clusters.…”

Section: Cluster-in-a-box Modelmentioning

confidence: 99%

Water emission tracing active star formation from the Milky Way to high-$z$ galaxies

Dutkowska¹,

Kristensen²

2022

Preprint

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Context. The question of how most stars in the Universe form remains open. While star formation predominantly takes place in young massive clusters, the current framework focuses on isolated star formation. This poses a problem when trying to constrain the initial stellar mass and the core mass functions, both in the local and distant Universe. Aims. One way to access the bulk of protostellar activity within star-forming clusters is to trace signposts of active star formation with emission from molecular outflows. These outflows are bright, e.g., in water emission, which is observable throughout cosmological times, providing a direct observational link between nearby and distant galaxies. We propose to utilize the in-depth knowledge of local star formation as seen with molecular tracers, such as water, to explore the nature of star formation in the Universe. Methods. We present a large-scale statistical galactic model of emission from galactic active star-forming regions. Our model is built on observations of well-resolved nearby clusters. By simulating emission from molecular outflows, which is known to scale with mass, we create a proxy that can be used to predict the emission from clustered star formation at galactic scales. In particular, the para-H 2 O 2 02 − 1 11 line is well-suited for this purpose, as it is among one of the brightest transitions observed toward Galactic star-forming regions and is now routinely observed toward distant galaxies. Results. We evaluated the impact of the most important global-star formation parameters (i.e., initial stellar mass function, molecular cloud mass distribution, star formation efficiency, and free-fall time efficiency) on simulation results. We observe that for emission from the para-H 2 O 2 02 − 1 11 line, the initial mass function and molecular cloud mass distribution have a negligible impact on the emission, both locally and globally, whereas the opposite holds for star-formation efficiency and free-fall time efficiency. Moreover, this water transition proves to be a low-contrast tracer of star formation, with I ν ∝ M env . Conclusions. The fine-tuning of the model and adaptation to morphologies of distant galaxies should result in realistic predictions of observed molecular emission and make the galaxy-in-a-box model a tool to analyze and better understand star formation throughout cosmological times.

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Tracing Embedded Stellar Populations in Clusters and Galaxies Using Molecular Emission: Methanol as a Signature of the Low-Mass End of the Imf

Cited by 4 publications

References 27 publications

Thermal Feedback in the High-mass Star- and Cluster-forming Region W51

Thermal Feedback in the High-mass Star- and Cluster-forming Region W51

Star-formation-rate estimates from water emission

Water emission tracing active star formation from the Milky Way to high-$z$ galaxies

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